Safety outlet

ABSTRACT

The device disclosed is an outlet which may be connected to a standard rubber insulated lamp cord without stripping the insulation and may be positioned at any point along the length of the cord. The cord piercing contacts are arranged to move with a clamp member which provides strain relief and which is so formed as to block the use of the outlet before the strain relief and the contacts are engaged and is further shaped to prevent the strain relief and the cord piercing contacts from being disengaged while a plug occupies the outlet.

Patented May 16, 1972 3,663,924

2 Sheets-Sheet 1 SAFETY OUTLET There are a number of other devices forattaching outlets along electrical conductors but in the known examplesof such devices special electrical conductors are required in specificshapes to accommodate the clamping mechanism. I know of the following:

Abramson 3, l 48,009 9/8/64 Messing 2,942,224 6/21/60 Platz et al.2,946,037 7/19/60 Smith 2,682,647 6/29/54 Carlson 2,856,592 /14/58 DeMask 1,805,572 5/19/31 SUMMARY OF THE INVENTION So far asl am'aware,none of the previous devices are capable of connections anywhere along astandard electrical cord using piercing contacts which do not requirestripping of the cord and in which the openings for the prongs of a plugare so covered that they are open only when the contacts are fullyengaged with the conductors of the cord and the strain relief is also inposition, the structure being such that the safety features cannot bedefeated. These objects are accomplished by providing an outlet bodywith a cord channel extending through it at one side. A strain reliefshaft is rotatable in the body and is provided with helical thread orcam members engagable with the body to cause it to move axially when itis rotated. The end of the shaft is so formed as to engage a cord in thechannel with great force but without damage to the insulation of thecord. Preferably, it has a round conical point. An optional recess maybe provided in the cord channel opposite the point so that the cord isbent as it is clamped. This optional feature provides extremely securestrain relief but has been found not essential because the clampingforce is very great without such a recess. A pair of slidable contactsmay enter the strain relief shaft and are provided with sharpenedpoints. In the embodiment shown in which the cord is a two conductorcord, these points are disposed at opposite sides of the cord channel toengage the respective conductors of the conventional flat lamp cord.Each contact is provided with a flange struck from the material of thecontact which is received in an annular channel or groove in the strainrelief shaft so that the contact is carried along with the shaft and isbent to extend along the side of the channel for the prongs. The head ofthe strain relief shaft is enlarged to cover the openings for the prongsof a plug and relieved to provide openings when turned to strain reliefposition. Because the cover for the prong openings is an integral partof the strain relief clamp and of the mechanism which advances thecontacts to pierce the conductors of an electrical cord, no connectioncan be made to the outlet until it is secured in a safe position on theelectrical cord with the prongs engaged with the conductors. By the sametoken, the prongs of a plug when inserted into the openings provided inorder to make electrical contact, become a lock which prevents movementof the strain relief shaft and thereby prevent accidental loosening ofthe strain relief or disengagement of the outlet contacts from theelectrical cord. Thus, a number of safety features are present.Engagement of the electrical contacts of the outlet with a cord issimultaneous with the provision of strain relief preventing damage tothe contacts and to the cord, and the outlet is unusable except whenstrain relief and electrical Contact cannot be broken. Also the partsrequired are few and simple.

Preferably the outlet may be loose on a cord having a fixed plug andfixed outlet at the ends, to prevent overloading the cord.

DRAWINGS ln the drawings,

FIG. l is a perspective view of a cord set having the safety outlet ofmy invention applied as a second outlet between the ends ofthe cord set.

FIG. 2 is a view showing the body of the safety outlet of my inventionopened at its midline.

FIG. 3 i s` an exploded view showing the clamping shaft and theelectrical contacts of-my safety outlet.

FIG. 4 is a top view of the safety outlet of my invention showing theplug prong openings exposed.

FIG. 5 is a top view of the safety outlet of my invention showing theplug prong openings covered.

FIG. 6 is aview like that of FIG. 2 showing the optional recess in thecord channel to enhance the effectiveness of the strain relief.

FIG. 7 is like FIG. 6 except that it shows the strain relief shaftrotated 90 to withdraw the contact from the electrical cord and blockthe plug prong openings so that the outlet is free to move to a newposition along the electric cord. FIG. 8 is a cross-sectional view online 8 8 of FIG. 2.

DESCRIPTION It will be noted that the structure shown has only threekinds of major parts. The two body shells required are identical; thetwo contacts required are identical; and a single strain relief shaft isrequired. The parts are also exceedingly easy to manufacture and toassemble. The body halves may advantageously be molded from plastic, asmay the strain relief shaft. The contacts are readily constructed onstandard machinery from a single piece of metal each. There is littlewaste if a strip of metal the width of the contact is used. All that isrequired for assembly is to place two of the contacts on either side ofthe strain relief shaft in half of the body shell. The other half ofthebody shell is placed on top and a pair of rivets are placed in the twoholes at the sides. This exceptionally simple and economical structureis in marked contrast to other devices of the kind shown in the priorart of which I am aware. In addition, it presents a combination ofsafety features not present in prior art of which I am aware.

The description and drawings herein are illustrative of the specificembodiments shown and are not intended to limit the invention, which isdefined by the appended claims.

As shown in the drawings, my safety outlet consists of a pair ofidentical body parts 10, a pair of identical contacts 30, and a strainrelief member 40.

The body parts 10 are preferably provided with a pair of openings l1,one on each side, to receive a pair of suitable fastenings such asrivets 12. A channel 13 is provided to receive an insulated electricalconduct 14, shown here as a standard, twoconductor lamp cord.

In the embodiments shown in FIG. 2, cord channel 13 is straight, whilein the embodiments shown in FIGS. 6 and 7 channel 13 has a depression 15into which the strain relief member 40 presses cord 14. Body 10 is alsoprovided with channel 16 to receive strain relief member 40 and contacts30 for axial movement into and out of channel l5. Channel 16 isinterrupted to provide an opening through which contacts 30 extend fromstrain relief member channel 16 into plug prong channels 17. The upperpart of body 10 is relieved sufficiently at 18, at the upper end of therespective plug prong channels 17 to make clearance to receive thecircular head 4l of the strain member 40. Finally, each body member l0is provided with a protuberence 19 (seen only in FIG. 8) which serves asa fixed reaction member against which strain relief member 40 pusheswhile it is moving axially or applying pressure to cord 14.

Electrical contacts 30 are generally U-shaped, having a shorter end 31which serves to make contact with another electrical device such as theprong of a plug similar to plug 14C. As shown in the drawings, end 3l ofcontact 30 extends into channel 17 of body 10 at a slight angle so thatupon insertion of the prong 14e of a plug similar to plug 14C, Contactend 31 will make electrical contact with it. End 3l is connected by abend 32 with a longer leg 33. Bend 32 is located near head 4l of strainrelief member 40 within channel 16 of body 10. Leg 33 is provided with aflange 34 which is preferably struck a plurality of contacts each havinga pointed end adapted to move axially to and from engagement with arespective conductor with said clamp means as said clamp means isrotated, openings in said body adapted to receive the prongs of anelectrical plug, and means attached to said clamp means to block saidprong openings until said clamp means and said points are moved axiallyinto said cord channel. 9. The device of claim 8 in which said body isprovided with an integral protuberance,

said clamp means comprising a shaft provided with a helical screw threadengaging said protuberance, said openings for said plug contactscomprising a pair of parallel channels extending at right angles to saidcord channel, said outlet contacts being U-shaped and having a short endportion of the U extending along the side of the respective plugopenings and a long leg portion of the U extending alongside the shaftof the clamp means, said shaft being provided with a circumferentialgroove and said outlet contact being provided with flanges entering saidgroove. 10. For making strain relieved contacts with an insulatedelectrical conductor, a body having a channel to receive said insulatedconductor, an electrical contact having a point adapted for axialmovement toward and into the channel and through the insulation to makeelectrical contact with said conductor,

a strain relief member adapted to move axially into contact with theinsulation of said conductor to apply pressure thereto against the wallof said channel,

an opening in said body providing access to said contact member formaking an electrical connection thereto, and

means operated by said strain relief member preventing access to saidlast mentioned opening when said strain relief member is not in aposition in which pressure is applied to said electrical insulation, andhaving an opening permitting such access when said member is in pressureapplying position.

ll. The device of claim 10 in which the contact and the strain reliefmember are connected for simultaneous axial movement into said channel.

12. The device of claim 10 in which the means preventing access to saidopening for making electrical contacts is also adapted to lock saidstrain relief member in its pressure applying position when anelectrical conductor extends through said opening for connection to saidcontact.

* it lk nited vStates Patent Proctor [451 May 16, 1972 [54] ELECTRICALCONNECTOR FOREIGN PATENTS 0R APPLICATIONS [72] Inventor; Richard D J.Proctor, Portsmouth, R 1 1,232,014 4/ 1960 France ..339/17 LC [73]Assignee: The United States of America as represented by the Secretaryof the Navy Primary Examiner-Joseph H. McGlynn Attorney-R. S. Sciasciaand Henry Hansen l 5 7 l ABSTRACT An* electrical connector forinterfacing a PC (printed circuit) board with external circuits. Anonconductive core, formed to engage the edgeof the PC board adjacent tothe printed circuit terminals, receives two rows of opposed contactsprings, each Spring having a bifurcated portion in the core forreceiving a contact pin of an external circuit and a base portionextending outwardly for engaging either side of the circuit board atselected terminals. The bifurcated portions of each spring are inwardlyinclined from their respective ends to form pin contact points developedfrom each other along their length. A nonconductive cover removablyfitted over the core and springs provides accessibility for springreplacement and protection against contact pin damage.

9 Claims, 2 Drawing Figures

1. In an electrical outlet for connection to an electrical cord withoutstripping the insulation from the cord, a body, a cord channel for saidcord through said body adapted to hold an insulated conductor in apredetermined position, a contact channel in said body and extendingtoward said cord channel, said contact channel being adapted to receivethe projecting prong of an electrical connector, a contact within saidbody, said contact having a portion in said contact channel adapted tomake electrical connection with a prong upon insertion of the prong intothe channel, said contact being provided with a pointed end, saidpointed end being directed toward said predetermined position of theconductor in said cord channel, and means to reciprocate said contactinto and out of said cord channel, said means including means separatefrom said sharpened end of said contact to secure said conductor in saidchannel, said means for reciprocating said contact further includingmeans to prevent reception of prongs into said contact channel when saidcontact is withdrawn from said cord channel.
 2. The device of claim 1 inwhich said means for moving said contact comprises a generallycylindrical shaft adjacent said contact, a helix on said shaft, fixedmeans on said body extending into engagement with said helix adapted tocause said shaft to move axially with respect to said body upon rotationof said shaft, and a rotatable connection between said shaft and saidcontact adapted to move said contact axially upon axial movement of saidshaft.
 3. The device of claim 2 in which the rotatable connectionbetween said shaft and said contact comprises a groove in said shaft anda protuberance on said contact extending into said groove.
 4. The deviceof claim 3 in which said protuberance on said contact consists of aflange extending into said channel, said flange being struck up from thematerial of which the contact is made.
 5. The device of claim 2 in whichsaid shaft is provided with a generally circular head extending radiallyfrom said shaft at the top of said body sufficiently to cover thecontact channel for reception of the prong of an electrical plug, and arecess in the margin of said head of sufficient depth to expose saidchannel for the reception of the said prong of an electrical plug, saidrecess being so positioned with respect to said helical means as toexpose said channel for reception of a plug prong only when said shaftis at its positioN axially furthest into said body.
 6. The device ofclaim 2 in which said shaft is provided with a generally conicalprotuberance at its inward end adapted to enter said cord channel whensaid shaft is in its axially inward position and bear against aconductor in said cord channel whereby it prevents movement of said cordwith respect to said body.
 7. The device of claim 6 in which the cordchannel is relieved axially away from said shaft at the point where saidshaft enters said cord channel whereby pressure of said shaft against acord in said channel forces the cord into the relief.
 8. In an electriccord set, a multiple conductor cord having a plug at one end and asingle outlet at the other end, a movable outlet intermediate the endsof said cord, said movable outlet comprising a body having a cordchannel through which said cord extends, cord clamping means movableaxially into and out of said channel, means to cause said axial motionof said clamp means upon rotation of said clamp means, a plurality ofcontacts each having a pointed end adapted to move axially to and fromengagement with a respective conductor with said clamp means as saidclamp means is rotated, openings in said body adapted to receive theprongs of an electrical plug, and means attached to said clamp means toblock said prong openings until said clamp means and said points aremoved axially into said cord channel.
 9. The device of claim 8 in whichsaid body is provided with an integral protuberance, said clamp meanscomprising a shaft provided with a helical screw thread engaging saidprotuberance, said openings for said plug contacts comprising a pair ofparallel channels extending at right angles to said cord channel, saidoutlet contacts being U-shaped and having a short end portion of the Uextending along the side of the respective plug openings and a long legportion of the U extending alongside the shaft of the clamp means, saidshaft being provided with a circumferential groove and said outletcontact being provided with flanges entering said groove.
 10. For makingstrain relieved contacts with an insulated electrical conductor, a bodyhaving a channel to receive said insulated conductor, an electricalcontact having a point adapted for axial movement toward and into thechannel and through the insulation to make electrical contact with saidconductor, a strain relief member adapted to move axially into contactwith the insulation of said conductor to apply pressure thereto againstthe wall of said channel, an opening in said body providing access tosaid contact member for making an electrical connection thereto, andmeans operated by said strain relief member preventing access to saidlast mentioned opening when said strain relief member is not in aposition in which pressure is applied to said electrical insulation, andhaving an opening permitting such access when said member is in pressureapplying position.
 11. The device of claim 10 in which the contact andthe strain relief member are connected for simultaneous axial movementinto said channel.
 12. The device of claim 10 in which the meanspreventing access to said opening for making electrical contacts is alsoadapted to lock said strain relief member in its pressure applyingposition when an electrical conductor extends through said opening forconnection to said contact.